Annular combustor for use with an energy system

ABSTRACT

An annular combustor has an annular inner shell, an annular outer shell and a dome end wall connecting the inner shell with the outer shell. A dam is positioned between the dome end wall and the exit end and extends radially from at least one of the inner shell and the outer shell to provide a reduced flow area passageway within the combustion chamber.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/200,946 filed May 1, 2000.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to combustors and more particularly, to annularcombustors used with an energy system.

2. Description of the Prior Art

Combustors are conceptually straightforward devices. They provide achamber in which a fuel and an oxidant, such as air, are combined andburned to create hot gases of combustion. In practice, however,designing an efficient combustor is a complex task. In order to extracta maximum available energy from the fuel, and to reduce emissions to aminimum level, a combustor must provide an environment in which completecombustion of the fuel can occur. Provisions must be made to thoroughlymix the fuel and oxidant. Where the fuel to be burned in the combustoris a liquid, such as diesel fuel, rather than a gas such as propane ornatural gas, the combustor must also provide some means for atomizingand evaporating the liquid before combustion can occur. The combustormust also include some means for igniting the fuel and oxidant mixture,as well as means for maintaining a stable flame following ignition.Annular combustors for use with energy systems are known, such as thatdisclosed PCT Application No. PCT/US97/22007, which is herebyincorporated by reference.

It is an object of the present invention to provide an annular combustorthat results in low NOx, CO, and unburned hydrocarbon emissions, as wellas resulting in efficient use of fuel.

SUMMARY OF THE INVENTION

An annular combustor is comprised of an annular inner shell having aninner surface and an outer surface, a coaxial annular outer shell havingan inner surface and an outer surface, and a dome end wall connectingthe inner shell and outer shell. The inner shell, the outer shell andthe dome end wall define an annular combustion chamber having a chamberwidth between the inner surface of the outer shell and the outer surfaceof the inner shell, wherein the chamber extends along a longitudinalaxis and has an exit end opposite the dome end wall. A dam is positionedbetween the dome end wall and the exit end and extends radially from atleast one of the inner shell and the outer shell. The dam defines areduced flow area passageway within the combustion chamber and channelssupplying secondary air to the combustion process.

Additionally, an annular combustor is comprised of an annular innershell having an inner surface and an outer surface, a coaxial annularouter shell having an inner surface and an outer surface and a dome endwall connecting the inner shell and outer shell, wherein the innershell, the outer shell and the dome end wall define an annularcombustion chamber having a chamber width between the inner surface ofthe outer shell and the outer surface of the inner shell, wherein thechamber extends along a longitudinal axis and has an exit end oppositethe dome end wall. A dam positioned between the dome end wall and theexit end and extending radially from at least one of the inner shell andthe outer shell, wherein the dam defines a reduced flow area passagewaywithin the combustion chamber. The combustion chamber has a primary zonedefined by the region of the combustion chamber between the dome endwall and the dam of the combustor, a secondary zone defined by theregion of the combustion chamber adjacent to the dam and a dilution zonedefined by the region of the combustion chamber between the dam and theexit end. The combustor further includes a means for providing fuel andair or oxygen into the primary zone, means for ignition provided in theprimary zone, a plurality of air or oxygen passageways defined in thesecondary zone, and a plurality of air or oxygen passageways provided inthe dilution zone.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional side view of a compressor/turbine includinga combustor made in accordance with the present invention;

FIG. 2 is a perspective view of a combustor in accordance with thepresent invention;

FIG. 3 is an end elevational view of the combustor in accordance withthe present invention;

FIG. 4 is a side elevational view of the combustor, shown in FIG. 2;

FIG. 5 is an enlarged detail of the encircled area shown in FIG. 3;

FIG. 6 is a side elevational view of an alternate embodiment of thecombustor in FIG. 1;

FIG. 7 is a side elevational view of another alternative embodiment ofthe combustor shown in FIG. 1; and

FIG. 8 is a side elevational view of an alternate embodiment of the damillustrated in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates an annular combustor 10 in accordance with thesubject invention connected to a compressor/turbine arrangement 100. Thecompressor/turbine arrangement 100 includes compressor blades 102, adiffuser 103, turbine blade nozzle vanes 104, and turbine blades 105positioned around a rotary drive shaft (not shown), which rotates abouta longitudinal axis X. The combustor 10, further illustrated in FIG. 2,is comprised of an annular inner shell 15, having an inner surface 17,and an outer surface 19. The combustor 10 furthermore has a co-axialannular outer shell 20, having an inner surface 22, and an outer surface24. A dome end wall 30 connects the inner shell 15 and the outer shell20, wherein the inner shell 15, the outer shell 20 and the dome end wall30 define an annular combustion chamber 35, having a chamber width Wbetween the outer surface 19 of the inner shell 15 and the inner surface22 of the outer shell 20. The chamber 35 extends along the longitudinalaxis X, and has an exit end 40 opposite the dome end wall 30. A dam 45is positioned between the dome end wall 30 and the exit end 40 andextends radially outwardly from the inner shell 15 to define a reducedflow area passageway 50 within the combustion chamber 35.

It should be appreciated and will be explained further that the dam 45may extend radially outwardly from the inner shell 15 as illustrated inFIGS. 1 and 2, or, in the alternative, may extend radially inwardly fromthe outer shell 20, or, in yet another alternative, may extend bothradially outwardly from the inner shell 15, and radially inwardly fromthe outer shell 20.

Returning to FIG. 1, within the compressor/turbine arrangement 100, anannular housing wall 108 is provided and defines an air intake passage110 positioned adjacent to compressor blades 102. An inner housing wall114, is positioned adjacent to the exit end 40 of the combustor 10 toenclose the combustion chamber 35. The combustion chamber 35, the airpath 118 and the turbine blades 105 are in fluid communication with eachother. An annular cooling area 119 is defined by a distal end 120 of theforward housing wall 114 and the outer shell 20 of the combustor 10. Theannular cooling area 119 allows for more dilution air toward the turbinenozzle vanes 104 and turbine blades 105.

Air entering the air intake passage 110 is directed through passageway118 along the exterior surface of the combustor 10, and is introducedinto the combustion chamber 35 through a number of passageways 125, 128,130 and openings 80 extending through the walls of the combustor and,furthermore, is introduced to the combustion chamber 35 at the end 120of passageway 118. A plurality of fuel/air mixing tubes 132 extendsthrough the wall of the combustor 10 to provide fuel delivery to theprimary zone 55 of the chamber 35. The fuel/air mixing tubes 132, whichare tubular in shape, are adapted to angularly direct liquid or gas fueland compressed air or oxygen into the primary zone 55 of the combustor10. An igniter 140 passes through the combustor 10 and into thecombustion chamber 35, where it may ignite the air-fuel mixture withinthe chamber 55 until the combustion is self-sustaining.

Directing attention to FIGS. 1 and 2, the combustion chamber 35 iscomprise of a primary zone 55, a secondary zone 65, and a dilution zone75. The primary zone 55 is the region within the chamber 35 between thedome end wall 30 and the dam 45. The secondary zone 65 is the regionwithin the chamber 35 generally circumferential with the dam 45. Thedilution zone 75 is the region within the chamber 35 between the dam 45and the exit end 40.

As previously discussed, the dam 45 illustrated in FIG. 2 extendsoutwardly from the inner shell 15. It is entirely possible, asillustrated in the schematic in FIG. 6, to supplement dam 45 with asecond dam 145 which may extend radially inwardly from the outer shell20 to define a passageway 150. In the alternative, as illustrated inFIG. 7, it is possible to entirely eliminate dam 45, such that the soledam within the combustor 10 is dam 145 extending radially inwardly fromthe outer shell 20.

Returning to FIG. 1, the dam 45 may be comprised of two distinct partwherein a first part 46, extending from the exit side 47 to thecircumferential edge 48 of the dam 45, is positioned adjacent to asecond part 49. The dam parts 46, 49 may be welded to one another or maybe held securely against one another by means of a common anchor plate.

Returning to FIG. 2, and additionally directing attention to FIG. 3, thedam 45 has a plurality of openings 80 extending therethrough to permitfluid communication between the inner surface 17 of the inner shell 15,and the outer surface 19 of the inner shell 15. The openings 80 mayextend radially through the dam 45.

As illustrated in FIG. 4, the dam 45 has a circumferential face 82 whichmay be angled relative to the longitudinal axis X, such that theopenings 80 extend toward the exit end 40 of the combustor 10. Thesecircumferential faces 82 may have an angle A between 0 degrees and 80degrees with the longitudinal axis X thereby directing fluid from theopenings 80 toward the exit end 40 of the combustor 10.

As illustrated in FIG. 3, the radially extending openings 80 are spacedapart may provide an interrupted pattern at the front side 85 of the dam45. As previously mentioned, the dam 45 may be supplemented with asecond dam 145 as illustrated in FIG. 6. Under these circumstances thesame features discussed with the single dam 45 may also be implemented.In the alternative, and as previously mentioned, dam 45 may beeliminated such that the single remaining dam is dam 145 and once againsimilar features may be applied to the single dam 145.

The dams 45 and 145 may extend radially from the respective inner shell15 or outer shell 20 a distance of less then one-half the chamber widthW. Preferably, the dams extend a distance of approximately one-third ofthe chamber width W. It should be appreciated in the instances of onedam extending from each of the inner shell 15 and the outer shell 20,each dam may radially extend the distance approximately one-third of thechamber width W.

As illustrated in FIGS. 1 and 2, the dam 45 may be an integral part ofthe inner shell 15 from which it extends. In actuality, the inner shell15 is formed to incorporate the shape of the dam 45 and, as a result,the dam is essentially hollow and the openings occur only at thecircumferential face 82 of the dam 45.

FIG. 8 illustrates another embodiment of dam 45. A deflector 155 islocated along the circumferential edge 48 of the dam 45 such that fluidpassing through the dam 45 is deflected toward the exit end 40 of thecombustor 10. Under these circumstances the openings 80 is in the wallof the dam 45 facing the exit end 40. The deflector assures a smoothuninterrupted flow of secondary air mixing with the primary fuel/airmixture in a direction toward the exit end 40 to assure no secondary airis introduced into the primary zone and furthermore provides a surfaceto accept the through flow of secondary air in an impinging coolingscheme.

Circumferentially spaced slotted sections 147 are provided about theexit end 40 of the outer shell for receipt of an exit wall to direct theproducts of combustion away from the combustor and toward, for example,the turbine blades.

In operation, compressed air or oxygen at, for example, 45 psig isprovided via a compressor and surrounds the outer surface of thecombustor 10. Fuel is directed by a fuel injector 135 toward respectiveinner surfaces of the angled fuel/air premix tubes 132 (FIG. 5).Compressed air and/or oxygen also flows into the angled fuel/air premixtubes 132 forming a rich fuel to air mixture. The angled tubes 132create a circumferential swirling action. The fuel/air mixture exits thetubes 132 into the first section at an angle B (FIG. 3). Preferably, theangle B is not great enough to direct the fuel/air or oxygen mixturedirectly or tangentially against the inner surface of the shell.Preferably, only enough air or oxygen is provided to create a rich fuelmixture. This rich fuel mixture is then ignited by the igniter 140. Ascombustion takes place, products of combustion (POC) are formed throughpartial combustion. The POC and other materials then flow toward the dam45 in this secondary zone 65. Additional compressed air and/or oxygenare directed in a radial direction through passageways 128 resulting ina lean mixture. Further, since the flow area of the combustion chamber45 is reduced in the secondary zone 65, the velocity of the mixtureincreases over that in the primary zone 55. The resulting mixture in thesecondary zone 65 is a lean mixture. Additional combustion takes placeand the mixture and POC travel toward dilution zone 75. Dilution air isadded into the dilution zone at passageways 125, 130 to provide therequired turbine inlet temperature, and desired low flame patternfactor. The POC's then leave the dilution zone 75, and are directedtoward turbine blades 105 via the turbine nozzle vanes 104.

It is thought the present invention and many of its intended advantageswill be understood from the foregoing description and that it will beapparent that various changes may be made in the form construction anarrangement of the parts thereof, without departing from the spirit andscope of the invention, or sacrificing all of its material advantages,the form herein before described merely preferred or exemplaryembodiments thereof.

1. An annular combustor comprising: a) an annular inner shell having aninner surface and an outer surface; b) a coaxial annular outer shellhaving an inner surface and an outer surface; c) a dome end wallconnecting the inner shell and outer shell, wherein the inner shell, theouter shell and the dome end wall define an annular combustion chamberhaving a chamber width between the inner surface of the outer shell andthe outer surface of the inner shell, wherein the chamber extends alonga longitudinal axis and has an exit end opposite the dome end wall; d) adam positioned between the dome end wall and the exit end and extendingradially from at least one of the inner shell and the outer shell,wherein the dam defines a reduced flow area passageway within thecombustion chamber, wherein the dam is generally perpendicular to one ofthe inner shell and the outer shell thereby defining a primarycombustion zone between the dam and the dome, a secondary combustionzone adjacent to the dam and a dilution zone between the secondarycombustion zone and the exit end of the chamber, and wherein the dam hasa plurality of bores extending therethrough.
 2. The annular combustoraccording to claim 1 wherein the dam protrudes radially outwardly fromthe inner shell.
 3. The annular combustor according to claim 1 whereinthe bores extend radially through the dam.
 4. The annular combustoraccording to claim 3 wherein the dam has a circumferential face which isangled relative to the longitudinal axis such that the bores provideopenings extending toward the exit end of the combustor.
 5. The annularcombustor according to claim 1 further including a deflector locatedalong a circumferential edge of the dam and angled to direct fluidtoward the exit end of the combustor.
 6. The annular combustor accordingto claim 1 wherein the radially extending openings through the dam arespaced apart to provide an interrupted pattern at the face of the dam.7. The annular combustor according to claim 1 wherein the dam protrudesradially inwardly from the outer shell.
 8. The annular combustoraccording to claim 7 wherein the dam has a plurality of bores extendingtherethrough to permit fluid communication between the inner surface ofthe inner shell and the outer surface of the inner shell.
 9. The annularcombustor according to claim 8 wherein the bores extend radially throughthe dam.
 10. The annular combustor according to claim 9 wherein the damhas an inner face which is angled relative to the longitudinal axis suchthat the bores provide openings extending toward the exit end of thecombustor.
 11. The annular combustor according to claim 9 furtherincluding a deflector located along a circumferential edge of the damand angled to direct fluid toward the exit end of the combustor.
 12. Theannular combustor according to claim 8 wherein the radially extendingopenings through the dam are spaced apart to provide an interruptedpattern at the face of the dam.
 13. The annular combustor according toclaim 1 wherein a first dam protrudes radially outwardly from the innershell and a second dam protrudes radially inwardly from the outer shell.14. The annular combustor according to claim 13 wherein the dam has aplurality of openings extending therethrough to permit fluidcommunication between the inner surface of the inner shell and the outersurface of the inner shell.
 15. The annular combustor according to claim14 wherein the bores extend radially through the dam.
 16. The annularcombustor according to claim 15 wherein the dam has an inner face whichis angled relative to the longitudinal axis such that the bores provideopenings extending toward the exit end of the combustor.
 17. The annularcombustor according to claim 9 further including a deflector locatedalong a circumferential edge of the dam and angled to direct fluidtoward the exit end of the combustor.
 18. The annular combustoraccording to claim 14 wherein the radially extending bores through thedam are spaced apart to provide an interrupted pattern at the face ofthe dam.
 19. The annular combustor according to claim 1 wherein the damextends circumferentially about the longitudinal axis.
 20. The annularcombustor according to claim 1 wherein the dam radially extends from oneof the inner shell or the outer shell a distance of less than ½ thechamber width.
 21. The annular combustor according to claim 20 whereinthe dam radially extends a distance of approximately ⅓ the chamberwidth.
 22. The annular combustor according to claim 1 wherein each damis an integral part of the shell from which it extends.
 23. An annularcombustor comprising: a) an annular inner shell having an inner surfaceand an outer surface; b) a coaxial annular outer shell having an innersurface and an outer surface; c) a dome end wall connecting the innershell and outer shell, wherein the inner shell, the outer shell and thedome end wall define an annular combustion chamber having a chamberwidth between the inner surface of the outer shell and the outer surfaceof the inner shell, wherein the chamber extends along a longitudinalaxis and has an exit end opposite the dome end wall; d) a dam positionedbetween the dome end wall and the exit end and extending radially fromat least one of the inner shell and the outer shell, wherein the damdefines a reduced flow area passageway within the combustion chamber,wherein the dam is generally perpendicular to one of the inner shell andthe outer shell thereby defining a primary combustion zone between thedam and the dome, a secondary combustion zone adjacent to the dam and adilution zone between the secondary combustion zone and the exit end ofthe chamber, and wherein the dam has a plurality of bores extendingtherethrough. e) wherein the combustion chamber has: i) a primary zonedefined by a front portion of the inner shell, a front portion of theouter shell, a front surface of the dam and the inner surface of thedome end wall; ii) a secondary zone defined by a circumferential surfaceof the dam and a coaxial portion of one or both of the inner shell orouter shell; and iii) a dilution zone defined by a rear portion of theinner shell, a rear portion of the outer shell, and downstream adjacentto the secondary zone and exit end of the combustion chamber; f) meansfor providing fuel and air or oxygen into the primary zone; g) means forignition provided in the primary zone; h) a plurality of air or oxygenpassageways defined in the secondary zone; and i) a plurality of air oroxygen passageways provided in the dilution zone.
 24. An annularcombustor comprising: a) an annular inner shell having an inner surfaceand an outer surface; b) a coaxial annular outer shell having an innersurface and an outer surface; c) a dome end wall connecting the innershell and outer shell, wherein the inner shell, the outer shell and thedome end wall define an annular combustion chamber having a chamberwidth between the inner surface of the outer shell and the outer surfaceof the inner shell, wherein the chamber extends along a longitudinalaxis and has an exit end opposite the dome end wall; and d) a first damand a second dam positioned between the dome end wall and the exit end,wherein the first dam extends radially from the inner shell and whereinthe second dam extends radially from the outer shell to define a reducedflow area passageway within the combustion chamber, wherein each dam hasa plurality of bores extending therethrough.
 25. The annular combustoraccording to claim 24 wherein the first dam and second dam are coplanarwith one another.